The invention relates to marine stern drives, and more particularly to the output coupler such as in Entringer et al U.S. Pat. No. 4,634,391.
A marine stern drive has a lower outboard gearcase having a vertical driveshaft driving a horizontal propeller shaft in a lower torpedo housing, a propeller mounted on the propeller shaft and driven thereby, a universal joint driving the vertical driveshaft at the top of the gearcase, and an output driveshaft driving the universal joint and extending through the transom of a boat and having a forward splined end. An engine output coupler has an axially splined opening therein receiving the forward splined end of the output driveshaft. This structure has been subject to spline wear on commercial fishing boat engines due to lack of lubrication and continuous low speed operation. Periodic lubrication is required to prevent premature spline wear. Relubrication typically requires removal of the drive unit from the boat transom assembly, and then reinstallation. This is undesirable because it is costly, time consuming, and necessitates down time.
Some commercial boat operators have drilled an axial bore into the driveshaft, and radial cross holes with grease fittings for feeding grease into the bore, and plugging the end of the bore at the end of the driveshaft.
The present invention provides a simple and expedient solution to the above noted problem, without requiring drilling of bores in the driveshaft. The present invention provides lubrication structure which traps and retains the grease to maintain lubrication of the splines, preventing loss of lubricant as the splines slide against each other during normal boat trim and steering cycles. This significantly reduces the need for periodic relubrication. Another significant advantage of the invention is that it enables the boat operator himself to replenish the lubricant retention system without having to remove the drive unit from the boat, or remove the boat from the water. This significantly reduces servicing requirements, expense and down time.
Another solution is shown in commonly owned copending application Ser. No. 07/178,456, filed Apr. 7, 1988, "Marine Stern Drive With Lubricated Output Coupler".